Fast heartbeat. My reports here.

I am a 27 year old female who weighs 62 kg. For the last 5 days I am having fast heartbeat beat for some time in a day and the other time I feel normal. I am also having shortness of breath but it is less now after visiting a doctor nearby. I am having slight pain in my left arm sometimes in my left shoulder, my forearm and sometimes in my left hand. Little gassy stomach. In the previous night suddenly I got up and found fast heartbeat otherwise my sleep patterns is normal.The doctor performed an ecg and chest x ray. My heart beat yesterday was 123. Blood pressure is normal. Please help me. Is there anything to worry about. What should I do to manage these symptoms. I am attaching my reports here.